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Whoa...77 ft...
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erobertg
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Post Whoa...77 ft... Reply with quote
I don't think you're going to have to get your antenna up 77 ft. to be effective. You're dealing with medium band not FM and they're different animals when it comes to propagation. Youre EH antenna is a close cousin to the Crossed Field Antenna which can be mounted at ground level or one top of a one story building. Another antenna the DDR is actually mounted close to ground.

The big thing for propagation is the ground wave at frequencies below 3 MHz. After you get a good ground you are at the mercy of your local soil conductivity. To give you some idea I selected two 1,000 watt radio stations operating at 1490 kHz at different parts of the country.

The first is WKVT from Brattleboro, VT which has soil conductivity value of 1.

http://www.radio-locator.com/cgi-bin/info?call=WKVT&service=AM

Click on the "View Coverage Map" and you'll notice that coverage area evends to aroun 25 miles.

Now check out KFON from Austin, Texas for their coverage map.

http://www.radio-locator.com/cgi-bin/info?call=KFON&service=AM

You'll notice the range is 3-4 times as far. The difference is the soil conductivity value is 15-30 and it shows up in greater range.

Two stations operating on the same frequency with the same wattage, omnidirectional antennas but different soil conductivity. The best thing you can do is have a good ground and the rest you're at the mercy of local conditions.

I think you'll do fine with a 30' mast. The big thing is to get away from wiring and large metal objects.
Sat Jan 29, 2005 6:13 pm View user's profile Send private message
Antler
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Location: Somewhere between the RJAA and EHAM airports

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Ero,

Interesting but not surprising about soil conductivity as I have had my own experiences .... I did swap a few emails with the guy who holds the patent on the EH antenna and here is what he said.....

He says that soil conductivity isn't a big an issue with the EH. He did say that for proper performance the antenna should be 1/8 wave above the ground and that performance should be equal to the performance of a standard 1/4 wave broadcast antenna with 120 radials."

One more comment from his email: "The EH Antenna is not a resonant antenna in the normal sense of the word, i.e., it is not some function of a wavelength because the radiation is developed at the antenna, not the far field. However, the antenna does have a tuning coil that is resonated with the capacity of the cylinders. Therefore the antenna can be tuned to any frequency over a very wide range. For example, the small AM Broadcast antenna works very well from 1200 KHz to above 2 MHz.

From what I have heard, reports on the performance amatuer bands have been exceptional for the EH.

BTW, The price on the commercial version (handles 10 KW) is $17,000. The low power version (500 watts) professionally made, custom for your frequency, is about $600 Euros.

Later....
Sat Jan 29, 2005 7:31 pm View user's profile Send private message
Antler
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Ero,

BTW, thanks for showing the Radio Locator web page. Very cool!


Sat Jan 29, 2005 7:43 pm View user's profile Send private message
erobertg
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Post EH Antenna... Reply with quote
Good point Antler. My ARRL Antenna Book says that only vertical polarized antennas use the ground wave. I checked with my Isotron literature and it has random polarized waves, whatever that is. Probably a crazy mix of horizontal, vertical and circular polarization. So I guess that putting my antenna higher would probability help. It sure better than putting (120) ¼ wave radial furrows into the earth with our lousy ground conductivity. I live in a border 1 to 2 ground conductivity so I should see my antenna as a self radiating unit. It will probably work better than a conventional antenna, at least in my neck of the woods.

This page on EH is quite informative, a lot of similarities to the Isotron.

http://www.eh-antenna.com/index.php?option=content&task=category&sectionid=6&id=11&Itemid=30

I notice there are quite a few different coils in the design…Have you worked out the windings?

P.S. Glad you liked Radio Locator, handy for AM and FM DX...
Sun Jan 30, 2005 3:41 pm View user's profile Send private message
Antler
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Ero,

Thanks again for the link, I hadn't seen that page yet.

Quote:
This page on EH is quite informative, a lot of similarities to the Isotron


Yeah, I found this out as I was doing my research. I am not sure how they would compare in performance as both "reportedly" have great operational efficiancy. The EH design seems like it would be more capable of using high power.

No, I haven't worked out the windings yet but don't think that will be much of a problem once I begin.

BTW, On the locator page, I live in the fringe of a particular station that I listen to and contour shown for that station is exactly right. The contour software that is available is amazing.

FWIW, I am thinking about trying to get a LPFM license and found an engineer that will, for a $1000, do a surrounding contour map for you. The goal of this exercise, for you to fit your signal contour inside existing contours.

Enjoy your weekend!


Sun Jan 30, 2005 6:06 pm View user's profile Send private message
erobertg
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Post EH Antenna... Reply with quote
Here is a simplified EH from a French site...I hope the translation works.

http://216.239.37.104/translate_c?hl=en&u=http://f5ixu.wathy.com/&prev=/search%3Fq%3Disotron%2B73%26start%3D80%26hl%3Den%26lr%3D%26sa%3DN

I read on another page that for 1200-1700 kHz that 8" dia x 48" long cylinders are used. I'd mount the unit on 3 1/2" (4.0 O.D.) white PVC pipe. The coil would be wound on the pipe and would have 70-80 turns of #14 house wiring for the primary coil. The cylinders look about 10" apart.

There is a small phasing coil between the cylinders that has to be worked out. I'm going to design the antenna using AutoCAD Solids and if you want a copy send me your email.
Tue Feb 01, 2005 2:39 am View user's profile Send private message
Antler
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Thanks, I did find the instructions in English on several different sites like this one.

http://www.wb5cxc.com/

The pictures of the french man and his antennas are very cool. I wonder how they work? There is a guy who lives about 30 clicks north who builds and uses these antennas. He is hard to catch, but I intend to talk to him before I begin my project. Unfortunately, I am at least two weeks from having any time to work on an antenna.


Tue Feb 01, 2005 3:33 am View user's profile Send private message
erobertg
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Post That was good site... Reply with quote
I will be checking this site...Thanx!
Tue Feb 01, 2005 4:11 am View user's profile Send private message
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